It is known in the art to provide programmable, numerically controlled (NC) processing devices of the type which include a programmable controller, a display unit coupled to the controller, means included in the controller for displaying on the display unit the NC program code lines, and an input unit, such as a keyboard, for entering programming data to the controller. In such a numerically controlled processing device, the NC program contains many lines of complex program code. Often it is desirable to edit portions of the NC program or create a NC program by copying portions of code from another NC program. However, because of the massive size and complexity of the NC program, it is often very difficult to locate quickly those portions of the code that are of interest.